Radio Frequency (RF) shielding is required on certain semiconductor devices and modules (hereinafter semiconductor device) in order to minimize Electro-Magnetic Interference (EMI) radiation from the semiconductor device. RF shielding is further required to prevent RF radiation from external sources from interfering with operation of the semiconductor device.
RF shielding is generally accomplished in one of three ways. A first method is to attach a metal can over the component after the component is attached to the motherboard. However, shield attach on the mother board has several problems. First, shield attach can be costly and a low yielding process. External shields soldered to the motherboard further require additional board space.
An alternative to the shield attached method described above is an embedded RF shield. In an embedded shield, the metal RF shield is directly attached to the semiconductor package substrate by means of solder or a conductive adhesive. The shield may be fully embedded within the mold compound of the finished package or can be exposed after assembly. In either case, the addition of a metal shield as a component attached to the top surface of the substrate is problematic for several reasons. First, the addition of a metal shield as a component attached to the top surface of the substrate requires a significant amount of additional space on the package substrate. Second, it can be difficult to transfer mold in and around the metal shield to fully encapsulate the semiconductor package. Shield attach is also problematic due to flux creep during shield attach which may cause delamination and extrusion issues.
The third method is the conventional conformal shield. Conformal shielding is the latest technology to support integrated circuit (IC) devices and System in a Package (SiP) modules shielding. The conformal shielding creates a metallic coating, which is attached to ground metal in the substrate to provide a full shielding result. Presently, the conductive coating is applied to non-conductive surfaces, i.e., mold compound, substrate, etc. The conductive coating can not be applied to exposed metal on the substrate, packages, and passive components as shorting will occur.
Therefore, a need existed to provide a system and method to overcome the above problem. The system and method would provide for RF shielding for exposed die components, non-encapsulated modules or motherboards.